Manufacture of diaryl sulphones



Patented May 7, 1935 UNITED STATES MANUFACTURE OF DIARYL SULPHONES James-Irvin Carr, Woodstown, N. J., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing.

21 Claims.

This invention relates to carbon compounds, more particularly diaryl sulphones, and a process for the production thereof.

The diaryl sulphones constitute a class of organic compounds which have been known for many years. Various methods have been proposed for their preparation. One of these methods is the reaction of sulphuric acid on an aryl hydrocarbon, or certain aryl hydrocarbon derivatives, in the liquid phase under specific operating conditions of temperature, acid concentration and water concentration.

Diaryl sulphones have also been produced by the reaction of oleum with the aryl hydrocarbons, or certain aryl hydrocarbon derivatives, in the liquid phase under suitable operating conditions. Another proposed method is by the introduction of sulphur trioxide vapors into the liquid hydrocarbon or hydrocarbon derivative. Still another method is by the action of the hydrocarbon on the sulphonic acid.

It has also been proposed to oxidize the diaryl sulphide or diaryl sulphoxide with a suitable oxidizing agent such as nitric or chromic acid, yielding the corresponding sulphone. In this manner, diphenyl sulfide has been oxidized to diphenyl sulphone. As another method of preparing diaryl sulphones, the aryl sulphonyl chloride may be condensed with the aryl hydrocarbon in the presence of anhydrous aluminum chloride, according to the usual Friedel crafts procedures.

It is an object of the present invention to provide a new and improved process for the preparation of diaryl sulphones. Another object is to provide a process by which diaryl sulphones may be obtained in relatively highyields. A further object is the provision of a process for the production of diaryl sulphones, characterized by case and economy of operation. Other objects will appear hereinafter.

These objects are accomplished according to the present invention whereby diaryl sulphones are produced by bringing together in the vapor phase sulphur trioxide and a volatile aryl compound containing a carbonhydrogen group in the aromatic ring, that is, an aryl hydrocarbon or an aryl hydrocarbon containing further substituents such as, for example, one or more of the'followlng groups: alkyl, hydroxyl, halogen and alkoiw. The product may be a single diaryl sulphone or a mixture of diaryl sulphones together with a varying quantity of other products such as, for example, sulphonic'acids and sulphone-sulphonic acids, depending largely upon Application June 20, 1933, Serial No. 676,759

the aryl compound employed initially. By treating the mixture of reaction products in the manner best suitable to the individual case, the diaryl sulphones may be obtained in varying yields, according to the'procedure followed and the materials entering into the reaction with the sulphur trioxide. It has been found that the yields of diaryl sulphone obtained according to this process are usually higher than those obtainable by the action of sulphuric acid or sulphur trioxide on the aryl hydrocarbon or hydrocarbon derivative in the liquid phase.

The above findings are particularly surprising in view of U. S. Pat. No. 1,321,991, issued on November 18, 1919, to Charles R. Downs. This patent states that upon reacting aromatic compounds in vapor phase with sulphur trioxide, aryl sulphonic acids are obtained, substantially pure, and free from either sulphuric acid or other bodies. It seems that Downs either did not carry his researches far enough or was misled by imperfect observations. For my researches, as reported below, show that the vaporphase reaction of aromatic compounds, especially those of the benzene series, with sulphur trioxide leads mainly to the production of sulphones rather than sulphonic acids, and the yields of these sulphones are in most cases greater than those obtainable by hitherto known processes.

The invention will be further understood, but is not limited, by the following examples, in which the parts are by weight.

Example I Seventy-eight parts of benzene and 84 parts of sulphur trioxide were separately but simultaneously run into two heated vessels at such a'rate that the liquids were rapidly vaporized. A stream of sulphur dioxide gas was passed through each vaporizer, carrying the evaporated benzene and sulphur trioxide into a suitable reaction vessel equipped with a fan for agitation and a means for cooling the reaction mixture. The reaction zone was maintained at a temperature of about 150 C. to

about 200 C. The rates of addition of benzene 'of the reaction vessel. When the reaction was complete, the reaction mixture was diluted with water, and the diphenyl sulphone was separated by filtration. The benzene-sulphonic acid was recovered from the mother liquor. The sulphone may be purified by crystallization from a suitable solvent suchas, for example, benzene, and/or by distillation.

It was found that the yield of diphenyl sulphone was of the order of about 50% whereas the yields obtained when the benzene was reacted with sulphur trioxide in liquid sulphur dioxide were not higher than about 15%, the principal product being benzene-sulphonic acid.

Example II Four hundred parts of chlorobenzene were added to a suitable vessel equipped with a means of heating and a reflux condenser. The

' chlorobenzene was heated to boiling. In a separate vessel about 440 parts of 65% oleum were heated to drive off sulphur trioxide vapors, which were then conducted into the vapors of the chlorobenzene in the first-mentioned vessel.

A vigorous reaction took place and considerable heat was liberated so that the. chlorobenzene boiled without further addition of heat. The rate of boiling was controlled by the rate of addition of the sulphur trioxide. When no 'more sulphur trioxide was available from the oleum, the reaction stopped and the mixture was drowned in water and filtered cold. The precipitate was purified by re-crystallization from benzene to give pure 4 4'-dichloro-diphenyl sulphone. The filtrate contained principally an oily layer of chlorobenzene which was separated and used again.- The aqueous solution contained chlorobenzene-sulphonic acids which may be recovered as the sodium salts by the addition of sodium chloride.

Example III Four hundred sixty parts of toluene were boiled in a closed vessel. In another vessel, strong oleum was heated. The vapors of toluene and sulphur trioxide thus formed were diluted with sulphur dioxide gas and were discharged into a reaction vessel in such proportions that a slight excess over equal molecular proportions of sulphur trioxide were always present. The reaction vessel was equipped with a fan for agitation and a means of cooling. The reaction took ,place with the evolution of heat and most of" the products of the reaction cooled in the reaction vessel. Another cooled vessel served to condense and separate any reaction products leaving the reaction vessel with the exit gas.

The products of the reaction were drowned in cold water and filtered; The separated precipitate consisted of mixed ditolyl sulphones.

Tolulene-sulphonic acids may be recovered from the filtrate as a by-product.

Example IV The dihydroxy-diphenyl sulphone was purified by dissolving it in boiling water, then cooling the solution, and filtering oil the sulphone which was but slightly soluble in cold water.

Example V One hundred eight parts of anisole were added with 40 parts of magnesium oxide to an agitated vessel equipped with a reflux condenser. The anisole was vaporized by boiling, and parts of sulphur trioxide vapor slowly passed into the anisole vapor with which it re- Example VI Five hundred parts of naphthalene were melted in a closed vessel and somewhat less than the theoretical amount of sulphur trioxide vapor was slowly added to the vapors above the melted naphthalene. The sulphur trioxide reacted at once with the naphthalene which was kept melted and vaporized by the heat of reaction. The contents of the vessel were drowned in water and filtered. The solid precipitate was steam-distilled to separate and recover the unchanged naphthalene. The naphthalene-sulphones were obtained by filtering the cold mixture after the removal of the naphthalene.

According to procedures described in the foregoing examples, other volatile aryl hydrocarbons or hydrocarbon derivatives may be converted to diaryl sulphones. Further specific examples of raw materials which may be converted to diaryl sulphones by reaction with sulphur trioxide in the vapor phase are paradichlorobenzene, paraxylene, diphenyl, alphaand beta-naphthol, and related compounds. As previously indicated, the structure of the products. obtainable according to the process of the invention will depend on the nature of the starting materials. For example, by the inter-action of benzene with sulphur trioxide, the only sulphone obtainable is diphenyl sulphone according to the following equation:

Similarly, only one product is obtainable from para-dichlorobenzene, as follows:

C1 C1 C1 SO2 2 2303 H250 Cl C] 1 However, when certain substances are subjected to this reaction, a mixture of isomers results, due to the structure of the starting materials. For example, naphthalene gives a mixture of the alpha:alpha'-, beta:beta-and a1pha:beta'- Beta, beta Similarly, chlorobenzene yields a mixture of 2:2'-, 2:-4'-and 4:4-dichlorodiphenyl sulphones.

As a further variation, if a mixture of two or more substances is subjected to the action of sulphur trioxide in the vapor phase, a more complex mixture of sulphones may result. For example, if a mixture of benzene and paraxylene in the vapor phase is subjected to the agent action of sulphur trioxide, the product obtained is a mixture of diphenyl sulphone, di-(paraxylyl) -sulphone and phenyl-(para-xylyl) -sulphone.

Starting materials which are substantially oxidized by sulphur trioxide to form quinones and the like are not desirable for the purposes of the invention.

The reactions may be carried out in almost any type of closed apparatus which is resistant to the corrosive action of the vapors. For example, the reaction vessel may consist of a tube so arranged that the sulphur trioxide and hydrocarbon or substituted hydrocarbon vapors enter one end and the reaction products leave at the other.

If the reaction is unduly vigorous, even under relatively mild conditions, the vapors of the starting material and the sulphur trioxide may be diluted with an inert gas or vapor such as, for example, sulphur dioxide, nitrogen and carbon dioxide. The diluent gases or vapors may be introduced into one or both of the vaporized reactants. Alternatively, the addition of the diluent vapors may be made in the reaction zone. In addition to the diluents mentioned, many other gases or vapors may be employed, the only limitation being that the diluent is substantially um'eactive under the conditions of thereaction with the reactants or the products of the reaction. It is sometimes desirable to vaporize the organic reactant by boiling it with an inert liquid which serves to keep it vaporized aswell as to dilute it. Tetrachloroethane may be cited as an example of such a compound.

As indicated by Example V, when the reaction is carried out in vapor phase above the aryl compound in liquid phase, it is'sometimes desirablev to 'add a non-volatile acid-binding the liquid phase in order to neutralize any su phur trioxide and/or sulphuric acid which may be absorbed in or mixed with the liquid and thereby minimize reaction in the liquid phase. Examples of acid-binding agents which may be employed are magnesium oxide, calcium oxide, calcium carbonate, lead oxide and sodium sulphite.

The reaction temperature may be varied over a wide range. In general, it maybe said that the most suitable temperature-is selected on the basis of the volatility of the reacting substances, the reaction being efiected at a temperature at which the substance may be readily vaporized. For example, if benzene is the starting material, the reaction may be carried out at a relatively low temperature whereas if a high boiling material such as diphenyl is used, the reaction temperature must be raised in order to obtain a sufficient amount of the material in thevaper phase. It is not necessary to carry out the react-ion at the boiling point of the material, since the organic reactant may be diluted with gases or vapors and used at temperatures much higher or lower than its boiling point. The upper temperature limits should be below temperatures causing the formation of substantial amounts of decomposition products.

The pressure under which the reaction is offected is subject to considerable variation but it is usually more convenient to work at or near atmospheric pressure. It should be understood, however, that hydrocarbons or substituted hydrocarbons of the character described may be reacted with sulphur trioxide at pressures above or below atmospheric to give diaryl sulphones.

By operating according to the process of the invention, it is possible to produce sulphones in a very good yield in a minimum amount of time. Furthermore, the process involves the use of one of the cheapest procurable raw materials, namely, sulphur trioxide, for the production of sulphones; The low materials cost and the yields make this process superior to former methods forthe preparation of. diaryl sulphones.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments thereof except asdefined in the appended claims.

.I claim:

v 1. A process. for the manufacture of a diaryl sulphone, which comprises reacting a volatile aryl compound, having at least one carbon-hydrogen group in thearomatic ring, in vapor phase with sulphur trioxide, and recovering the formed diaryl sulphone from the reaction mass.

2. The process which comprises reacting the vapors of a volatile aryl compound, which has at least one carbon-hydrogen group in the ring and which is not readily oxidized by sulphur trioxide, with the vapors of sulphur trioxide, and recovering the diaryl-sulphone thus formed from the reaction mass.

3. The process which comprises reacting the vapors of a volatile aryl compound. of the benzene series, which has at least one carbon-hydrogen group in the ring and which is not readily oxidized by sulphur trioxide, with the vapors of sulphur trioxide, and recovering the diarylsulphone thus formed fromthe reaction mass.

4. The process of producing a diaryl sulphone, which comprises heating a volatile aryl compound having at least one free position in the ring to a temperature suflicient to volatilize part of the compound, mixing the vapors with gaseous sulphur trioxide, collecting the reaction product and separating its diaryl sulphone content from excess initial materials and by-product aryl-sulphonic acids.

5.. The process of producing a diaryl sulphone, which comprises heating a volatile aryl benzenoid compound having at least one free position in the ring but having no substltuents which are readily oxidizable by means of sulphur-trioxide,

to atemperature suflicient to volatilize part of the compound, mixing the vapors with gaseous sulphur trioxide, collecting the reaction product and separating its diaryl sulphone content from excess initial materials and by-product aryl-sulphonic acids.

6. The process of producing a diaryl sulphone, which comprises heating a volatile aryl compound having at least one free position in the ring to a temperature suflicient to volatilize part of the compound, mixing the vapors with gaseous sulphur trioxide and with an inert gaseous diluent, and separating the formed diaryl-sulphone from excess initial materials, inert diluent, and byproduct aryl-sulfonic acids.

7. The process of producing a diaryl sulphone, which comprises heating a volatile aryl compound having at least one free position in the ring to a temperature suflicient to volatilize part of the compound, sweeping through the vapors a gaseous inert diluent and mixing the resulting mixture of gases with gaseous sulphur trioxide, cooling the reaction mass to liquefy the reaction product. and separating its diaryl-sulphone content from by product aryl-sulphonic acid.

8. The process of producing a diaryl sulphone, which comprises heating a volatile aryl compound having at least one free position in the ring to a temperature suflicient to volatilize part of the compound, passing into the vapors gaseous sulphur trioxide continuously until reaction has substantially ceased, diluting the reaction mass with water, cooling and recovering the precipitated diaryl-sulphone.

9. The process of producing a diaryl sulphone, which comprises heating a volatile aryl compound having at least one free position in the ring, in the presence of an acid absorbing agent, to a temperature sufiicient to volatilize part of the compound, passing gaseous sulphur trioxide into said vapors until reaction has substantially ceased, steam distilling the reaction mass to remove excess initial materials, filtering the remaining aqueous suspension, and extracting from the filter cake its diaryl-sulphone content.

10. A process for preparing a diaryl sulphone of the benzene series, which comprises heating an aryl compound of the benzene series to form vapors of said compound, mixing said vapors with sulphur dioxide and sulphur trioxide, the quantity of sulphur trioxide being slightly in excess of one mole per mole of aryl compound vaporized, collecting the reaction product, and recovering therefrom the diaryl-sulphone formed in the reaction.

11. In the process of producing a sulphur and oxygen containing organic compound by reacting an aryl compound with sulphur trioxide in vaporphase, the step which comprises recovering a diaryl-sulphone from the reaction mass.

12. In the process of producing a sulphur and oxygen containing organic compound by reacting an aryl compound with sulphur trioxide in vaporphase, the step which comprises separating the diaryl-sulphone formed in the reaction mass from excess initial-materials and by-product aryl-sulphonie acids.

13. In. the process of producing a sulphur and oxygen containing organic compound by reacting an aryl compound with sulphur trioxide in vapor-phase, the step which comprises diluting the reaction mass with water and cooling,

whereby to crystallize out the diaryl-sulphones formed in the reaction mass while leaving any by-product aryl-sulphonic acids in solution.

14. In the process of producing a sulphur and oxygen containing organic compound by reacting an aryl compound with sulphur trioxide in vapor-phase, the step which comprises diluting the reaction mass with water, cooling and filtering, whereby to separate the diaryl-sulphones formed in the reaction mass from the watersoluble aryl-sulphonic acids formed in the same mass.

15. In the production of diaryl sulphones by the reaction of sulphur trioxide with a volatile organic compound containing a carbon hydrogen group in the aromatic ring, the steps which com-.- prise adding to said aryl compound in liquid phase a non-volatile acid-binding agent, and efiecting the reaction in vapor phase above the aryl compound in liquid phase.

16. In the process of producing a sulphur and oxygen containing organic compound by reacting an aryl compound with sulphur trioxide in vapor-phase, the step which comprises vaporizing partly a liquid phase of said aryl compound, eifecting the contact between the aryl vapors and sulphur trioxide in the vapor-saturated space above said liquid phase, maintaining the entire mass at a temperature suflicient to supply fresh vapors of the aryl compound as reaction proceeds, and feeding in the vapors of sulphur trioxide continuously as they are being used up by the reaction.

1'7. A process as in claim 16, in which the liquid phase is mixed with an acid binding agent adapted to react with sulphur trioxide, whereby to minimize reaction between the sulphur trioxide fumes and the liquid phase of the aryl compound.

18. A process as in claim 16, in which the liquid phase contains an acid binding agent of the group consisting of oxidesand carbonates of magnesium, calcium and lead, whereby to neutralize such quantities of sulphur trioxide as pass into the liquid phase and minimize reaction in the liquid phase.

19. The process of producing diphenyl sulphone which comprises separately vaporizing about 78 parts of benzene and about 84 parts of sulphur trioxide, diluting each gas with sulphur dioxide, bringing the two mixed gases together at a temperature of about 150 C. to about 200 C., collecting the reaction product, diluting the same with water, and filtering oil the crystallized diphenyl sulphone.

20. In the production of diaryl sulphones by the reaction of sulphur trioxide with a volatile aryl compound of the benzene series containing a carbon-hydrogen group in the aromatic ring, the step which comprises effecting the reaction in vapor phase above the aryl compound in liquid phase whereby the heat of reaction serves to vaporize the aryl compound.

21. In the production of diaryl sulphones by the reaction of sulphur trioxide with a volatile aryl compound of the benzene series containing a carbon-hydrogen group in the aromatic ring, the step which comprises efiecting the reaction in the vapor phase above the aryl compound in liquid phase, said liquid phase containing a nonvolatile acid-binding agent.

JAMES IRVIN CARR. 

